We need to implement energy monitoring in our smart plug. We are considering 2 ICs HLW8012 and BL0937 for this purpose and following are their reference designs in their data sheets.
I am trying to understand why multiple series resistors are used on VP pin in both reference designs (6 resistors of 470K in HLW8012 and same 6 resistors of 200K in BL0937). Taking an example of BL0937 I am wondering why 1.2MOhm is not used in case of BL0937. 6 series resistor of 200K also gives same resistance 1.2Ohm and we could select resistor power of 1.2MOhm same as any of 200K resistor wattage.
Does multiple series resistor on VP pin serves any other purpose except for ease of availability?
We are struggling with limited size and wand to reduce components to as minimal as possible. Our preference is to use single 1.2MOhm resistor instead of six 200K resistor.
Your help to understand the logic behind multiple series resistor on VP pin will be much appreciated.